Method of separating and concentrating butadiene



May 8, 1945- c. E. MORRELL TAL 2,375,576

METHOD OF SEPRATING AND CONQENTRATI-NG BUTADIENE Filed July 22, 1942- Adu/117 man1. mbof k. M+ Mr# Fowl? Patented May 8, 1945 UNITED STATE METHOD F SEPARATING AND CON CENTRATING BUTADIENE Charles E. Morrell, Roselle, and Miller W. Swaney,

Linden, N. J., assignors .to Standard Oil Development Company, a corporation of Delaware Application July 22, 1942, Serial No. 451,840

4 Claims.

This invention relates to improvements in the separation and concentration of diolens and particularly to the separation and concentration of dioleins using a cuprous salt solution as the absorbent.

The selective afnity of cuprous salt solutions forunsaturated hydrocarbons is well known and ammoniacal cuprous acetate solutions have been used for the preferential extraction of diolefins such as butadiene, from mixtures of hydrocarbons containing olefins and diolens. 'lIhe absorption of the diolefins in the cuprous salt solution was generally carried out by passing the hydrof carbon mixture as a gas through a liquid solution of the cuprous salt. One objection found in this process was that the saturation capacity of a cuprous salt solution decreases with increasingv temperature, for example, the volumes of pure butadiene gas absorbed at 40 F. are 16 volumes for each volume of the cuprous salt solution, at 50 F. 15 volumes, at 70 F. 10 to 1i volumes, and at 100 F. 5 to 6 volumes. i

Another disadvantage found in using this process was in the low-amounts of diolefins absorbed per pass. Likewise, a substantial portion of diolens were not absorbed by the cuprous salt sointion, a substantial quantity remaining in the spent mixture. l

When a hydrocarbon mixture, for example one composed of hydrocarbon Where each hydrocar. bon has only four carbon atoms to the molecule, is liquefied and passed through a liquid solution of a cuprous salt emulsincation usually occurs. This emulsions, etc. It was also found that the diolefins absorbed in the lcuprous salt solution on being expelled are of a higher concentration, that is, of at least 95% diolens, for example when butadiene is separated from a mixture of hydrocarbons having 4 carbon atoms to the molecule.

The attached graph shows the effect of temperature, and of dissolved butadiene, on the viscosity of a 3.8 normal copper solution. It follows that solutions this viscous might eastily cause diculties when employed as the continuous phase in i liquid phase extractions. Contrasted to these Very very high viscosities is the very low viscosity of C4 hydrocarbons- The attached. figure shows the viscosity of the copper solution at 0 C. to be about l1 centistokes. `That for C4 hydrocarbons underv .the same conditions is about-0.35 centistoke.

Therefore by employing C4 as the continuous phase in a liquid-liquid extraction, the diiculties `caused by the more viscous copper solutions tend to disappear.

The following examples will serve to illustrate -the marked advantages of continuous Ci-phase extractions over continuous copper-phase extractions of butadiene-containing C4 stocks.

EXAMPLE l feed dispersed therein. The summarized data emulsiiication slows yup the process as the emulfollow:

Table 1 Theor.

Y Copper Liquid Butadiene Temp. of Butadione C 5115312' ed I roduct pu- Cleanup saturation of solution C. reed in C. exiracin spent copper my percent of C. copper feed rate rate feed tion i solution butadiene solution Gah/hr. Gat/hr. Per cent F. Per cent Cu. ftJgaL. Per cent Per cent Per cent sions must be broken before a desired separation is obtained.

An object of this invention is to provide a method in which the volume of the dioleiins separated from the hydrocarbon mixture is materially increased.

This and other objects will be understood on reading the following description. y

According to this present method it was found if the hydrocarbon mixture is liquefied by the use of pressure or lowering of the temperature or a combination of the two and maintained in a continuous liquid phase, that cuprous salt solutions when passed through this liquid continuous phase of hydrocarbons, will absorb a larger quantity of These data indicate that no improvement in the extraction of diolen is obtainable over that obtained with the gas phase extraction of butadiene from C4 cuts with similar copper solutions, However, the next example shows the improvement afforded by continuous C4 phase extractions.

EXAMPLE 2 the desired 'dioleiins without forming undesirable no persing the copper solution therein. Other methods such as turbine type mixers may be used to contact the hydrocarbons and the `cuprous solution.

with a cuprous salt solution by -tllling and contin- 4 ouslyadding to and withdrawing lfrom a vessel the liquid hydrocarbon as continuous phase, con- Table 2 v Per cent Per cent Product Per cent Cu. soln. Solution Liq. C4 Temp. of exl Ci dissolved Per cent of Cur norm. feed rate feed rate glg traction Blgl by soin. geutf C4 cleanup ghfe'usg Gala/nf. Gaza/hr. F. ou. fit/gaz. 2. 7 67 8. 6 30. 3 `1634 2. 43. 4 1. 12 96. 5 94 76 2. 7 54 7. 4 29. 2 10-32 v0. 2 l. 25 95. 0 99 83 2. 6 65 9. 9 29. 7 17-34 3. 4v l. 23 94. 2 l 91 84 We claim: tinuously adding and passing 'through the liquid 1. The method of separating and concentrating butadiene which comprises, passing a hydrocara bon liquid that is normall f gaseous at normal atmospheric temperatures in countercurrent flow with a cuprous salt solution by lling and continuously adding to and withdrawing from a Vessel the liquid hydrocarbon as continuous phase, continuously adding and passing through the liquid hydrocarbon a cuprous salt solution as discontinuous phase, subjecting the separated cuprous salt solution to heat and separating butadiene.

2. The method according to claim l in which the cuprous salt solution is ammoniacal cuprous acetate.

3. The method of separating and concentrating a diolei'ln which comprises passing a hydrocarbon liquid containing a'diolen in countercurrent flow hydrocarbon a cuprous salt solution as discontinuous phase, subjecting the separated cuprous salt solution to heat and separating a diolen.

4. The method of separating and concentrating a dioleiin which comprises passing a hydrocarbon liquid containing a diolein in countercurrent flowV with a cuprous salt solution by iillng and continuously adding to and withdrawing from a packed tower the liquid hydrocarbon as continuous phase, continuously adding and passing through the liquid hydrocarbon in the packed tower a cuprous salt solution as discontinuous phase, subjecting the separated cuprous salt solution to heat and separating a diolen.

CHARLES E. MORRELL. v MILLER w. swANEY. 

